Growing cities and economies have a drastic impact on the future of the earth. New Delhi being one of the prime cities, having a boosting economy and ever-growing population, faces the challenge of rapid urbanisation without considering the environmental implication. Poor urban microclimatic conditions in Indian cities and increased hazards from air pollutions have resulted in declined outdoor human thermal comfort.

Urban challenges are increasing at a fast rate due to the rapid growth of cities around the world by the end of the last century. This has been notable in terms of the environment and the impact urbanisation has on it as well as human thermal comfort. With these cities becoming more urban and vehicular centric, emissions from vehicles, domestic pollution, loss of breathable green spaces and heavy dependence on fossil fuels in many power sector industries have all accumulated and contributed to urban sickness.

Urban thermal comfort and air pollution are two of the signs of urban disease that has become an area of major concern demanding global attention. The city of New Delhi particularly has been exposed to high levels of pollutants and the hot and humid climate from the months of March-October make outdoor urban areas highly uncomfortable and non-existent. A constant surge is also observed in the PM2.5 levels in winter months.

The statistics presented in the study are based for a typical urban setting in one of the 17 District centres in New Delhi utilising the computational tool ENVI-met as a base to analyse typical summer conditions along with Grasshopper and Eddy 3D, investigate the potential impact of all the factors on outdoor thermal comfort. The strong impact of urban vegetation, pavement albedos and façade greening are highlighted.

The study projects a strategic toolkit to mitigate the impact of rising thermal discomfort and pollution levels with the help of simple nature-based solutions. The analysis has been carried out into 6 scenarios with revised design interventions that are based on a rigorous on site and analytical analysis of local microclimatic conditions as well as the investigation with the end users. Climate conscious and low-cost solutions are adopted in these urban plazas and streets and their efficiency aided with the help of analytical simulations in ENVI-met

The simulations and site observations showed a clear decrease in UTCI temperatures in the plazas and internal streets by up to 3C while areas under shade further dropped down by 2C.  The effect of vegetation was the most successful in mitigating the high temperatures, improving the urban albedo decreased the surface temperature but showed an increase in surrounding air temperature.  Green roofs and facades greatly helped reducing the surrounding air temperatures but failed so in plazas or streets greater than H/W ratio of 0.9. The results, simulated for 2pm on 21 of June as the worst-case scenario, showed a drop in Mean Radiant Temperature levels with the increase in urban vegetation and grass cover.

Areas shaded from the existing built mass showed a further decrease in MRT with UTCI temperatures lowering from extreme heat stress to moderate heat stress. Urban greens further helped lowering the extreme heat stress in plazas and internal streets but showed an increase of 5-10μg/m3 in PM2.5 levels along the North and West of the site.

These design interventions could be applied to similar urban fabric all along the city to have a major impact on the overall climate resilience of the city. Although, the study focused on a typical urban zone, the interventions and strategies can also extend to similar urban environments with similar temperature conditions. The study could provide a base for analysis under the Smart Cities umbrella as a sub part to tackle against existing impacts of the built environment and as a pilot case to be implemented in on-going projects. The study also speculates future climate scenarios which will see a rise in average temperature conditions and precipitation graphs, designing for the future is now more than important to discuss and act for.